Race Fuel Question and Detonation
What do the Initial and final boiling point of a race fuel determine in reality. I'm having some knock issues. The car was tuned on C16
Specification Sheet: VP C-16 Specific Gravity: .735 @ 60°F Lead: Leaded Color: Blue Motor Octane: 117 RVP: 1.85 Oxidation Stability (min.) 1440+ Distillation: 10% evap @ 211.5°F 50% evap @ 213.1°F 90% evap @ 215.8°F E.P. @ 233.3°F but I'm running This: Specific Gravity 0.715 Antiknock Index (R+M)/2 112 RON, Research Octane 114 MON, Motor Octane 110 Reid Vapor Pressure 8 Distillation, ºF Initial Boiling Point 90 10% Evaporation 155 50% Evaporation 215 90% Evaporation 235 Final Boiling Point 260 Oxidation Stability, Min 1440+ Copper Strip Corrosion No. 1 Existent Gum, mg/100ml 1 Whats the difference? Also what would this fuel below do differently? Specification Sheet: VP Blue Specific Gravity: .717 @ 60°F Lead: Leaded Color: Blue Oxidation Stability (min.) 1440+ Motor Octane: 108 R+M/2: 109 Research Octane: 111 RVP: 7.20 Distillation: 10% evap @ 140.1°F 50% evap @ 214.0°F 90% evap @ 248.4°F E.P. @ 389.3°F I'm NOT leaning out. Maybe factory ignition is not doing well enough. 16psi using NGK 105 race plugs |
Dunno about the boiling points but the obvious thing is that the fuel spec that you're running is 7 points lower in MON than the C-16 it was tuned on. And you're having knock issues? The Blue in the last line is even lower. Where is your question here?
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What do the Initial and final boiling point of a race fuel determine in reality.
I don't see where 117 vs 110 octane would make a difference at 16psi but I guess if it was tuned on C16 it really would make a difference? |
If your timing was advanced to be ok with higher octane, then you will knock with lower octane. Sounds like you were tuned without much safety factor...
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Would water/alchohol injection help?
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More octane would help.
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http://www.faqs.org/faqs/autos/gasol.../preamble.html
The abridged version is that a lower boiling point relates to higher octane. The rub is that fuels that boil at a very low point may vapor lock more easily. |
Here is something else to think about: In addition to the big octane difference between your fuels, there is a huge difference in vapor pressure between the first fuel and the other two fuels.
We have been doing some testing with alternative fuels at work, and there seems to be a correlation between high vapor pressure and ignition delay; a high vapor pressure fuel takes longer to start burning. Once it does start burning, then it can burn rougher than a low vapor pressure fuel. I don't know why this happens; it is just something that I have observed. Can anyone explain? |
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